Question: Liang bought a basket of apples to make pies for her friends. The basket of apples weighed $p$ pounds. Before she had time to make the pies, she ate $3$ pounds of apples. There are $17$ pounds of apples left to make pies. Write an equation to describe this situation. What was the total weight of the basket of apples?
The weight of the basket of apples was ${p}$ pounds. Liang ate ${3}$ pounds of apples, and there were ${17}$ pounds left to make pies. We can represent the total number of pounds of apples left to make pies as a difference: ${p} - {3}$ We know there were ${17}$ pounds of apples left to make pies. We can set these two expressions equal to describe this situation with an equation: ${p} - {3} = {17}$ Other ways to represent the situation with an equation include: ${17} = {p} - {3}$ or $ p ={17} + 3$. Now we can solve for ${p}$. Add ${3}$ to both sides of the equation to get ${p}$ by itself: $\begin{aligned} p -{3} +{3} &= {17}+{3} \\ \\ {p} &={20} \end{aligned}$ The following equation matches this situation: $p-3=17$ The total weight of the basket of apples was $20$ pounds.